C-reactive Protein (CRP) Overview

C-reactive protein (CRP) is a marker of inflammation in the body. Therefore, its level in the blood increases if there is any inflammation in the body. C-reactive protein, along with other markers of inflammation (erythrocyte sedimentation rate, or ESR) are also sometimes referred to as acute phase reactants. C-reactive protein is produced by the cells in the liver.

Although the c-reactive protein level does not provide any specifics about the inflammatory process going on in the body (such as the location of the inflammation), it has been linked to atherosclerotic vascular disease (narrowing of blood vessels) by many studies. Atherosclerosis of blood vessels is thought to have an inflammatory component, and this may explain the link between this process and elevation of c-reactive protein.

Atherosclerosis can exist in varying stages. The basic theory suggests an injury to the blood vessel walls that occurs slowly over time. The site of initial injury then may become a focus for plaques to form, which contain inflammatory cells, cholesterol deposits, and other blood cells which are covered by a cap inside the lining of the blood vessels. This may represent a stable area of narrowing, or atherosclerosis, with mild inflammatory activity. These lesions can develop throughout the body in different degrees, and they can increase in size over time. Occasionally, the cap on one of these plaques can rupture and cause a more acute inflammation that results in impairment of blood flow in the involved vessel, leading to heart attacks or strokes when this occurs in the coronary arteries or arteries within the brain, respectively.

Picture of cholesterol plaque build-up and a blood clot, which can lead to a heart attack